1. Field of the Invention
The subject invention relates generally to a valve assembly for a pressure vessel, and more particularly, to a valve assembly for a pressure vessel containing a fire extinguishing agent used on an aircraft that includes a low pressure frangible seal supported by a poppet valve.
2. Description of Related Art
Firefighting in commercial and military aircraft often requires equipment which uses compressed fire extinguishing agents, such as halons, halon alternatives, or similar materials. These fire extinguishing agents are stored in suitable containers under a pressure of between 300-1200 psi, depending upon the application.
Some of these containers have an outlet that is closed with a leak-tight frangible closure membrane or rupture disc, as disclosed for example, in U.S. Pat. No. 7,434,628 to Scheidt. The closure membrane permits the container to be fluidly connected to a distribution pipe system by destroying the membrane, for example by igniting a pyrotechnical device. As soon as the membrane is destroyed by the pyrotechnical device, the fire extinguishing agent flows through the pipe system to an enclosed space where a fire has started.
A nozzle connected to the discharge end of the pipe system distributes the fire extinguishing agent in the enclosed space to suppress the fire. The pyrotechnical device is usually remote controlled through an electrical switch located in the cockpit of the aircraft. Fire detectors are installed in the enclosed space and provide a warning signal in the cockpit so that the release of the fire extinguishing agent can be immediately triggered by a crew member or automatically.
Because the fire extinguishing agent is maintained under pressure, the frangible closure membrane is continuously under stress and therefore susceptible to opening inadvertently, and thereby releasing the fire extinguishing agent prematurely or otherwise unnecessarily, at great expense.
It would be beneficial therefore, to provide a mechanism for supporting a frangible closure membrane or rupture disc while it is under pressure, to prevent the inadvertent or otherwise premature release of fire extinguishing agent from a pressure vessel. It would also be beneficial to remove the pyrotechnical device from the system, since it requires special handling and shipping.